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BOTANY OF CROP PLANTS 



types. The rachis is strongly compressed. Opposite each 

 point on the rachis where the spikelets stand, there is a 

 sharply defined horizontal cushion (Fig. 48). This dis- 

 tinguishes the barley rachis from that of wheat and rye. 

 Furthermore, the single joints of the barley rachis are 

 straight, while in wheat and rye they are bent. 



Fig. 49. — ^.-triplet of spikelets of six-rowed barley (Hordeum vulgare 

 hexastichon) ; note that there are three fertile spikelets at the rachis joint; 

 B, triplet of spikelets of two-rowed barley (H. distichon); the two lateral 

 spikelets are sterile; C, single spikelet of hooded barley (H. vulgare tri- 

 f urcatum) . 



At each joint of the rachis, there are three spikelets, each 

 one-flowered (Figs. 49 and 50). The lateral spikelets of each 

 triplet are sometimes imperfect, as in two-rowed barley. 

 Each spikelet is on a short branch or rachilla, which is pro- 

 duced beyond the flower and appears as a bristle (Fig. 51) 

 lying within the groove of the grain. As in wheat, there is 



